Trapping and Recombination Centers in Cesium Hafnium Chloride Single Crystals: EPR and TSL Study

Buryi, M.; Král, Robert; Babin, V.; Paterek, Juraj; Vaněček, V.; Veverka, Pavel; Kohoutková, Martina; Laguta, V. V.; Fasoli, M.; Villa, Irène; Cova, Francesca; Vedda, A.; Nikl, M.

doi:10.1021/acs.jpcc.9b05760

Cited by 19 publications

(17 citation statements)

References 40 publications

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“…We note that instrumental limitations inhibit similar quantitative or time-resolved analyses of the Cs 2 ZrCl 6 NCs, which requires deeper UV excitation. The combination of large Stokes shifts and broad, asymmetric PL features suggests radiative recombination may originate from self-trapped excitons, which has been reported for similar compounds such as Cs 2 HfCl 6 . − The lack of subgap contribution to the PLE spectrum of the Cs 2 ZrBr 6 NC thin films also indicates that radiative recombination is not due to permanent defect states . The similar PLQY values of the bulk powder, NC suspensions, and NC thin films support the hypothesis that (i) the self-trapped exciton emission is intrinsic, related to the bulk, and (ii) the emission, consequently, is not strongly dependent on the crystallite size for the sizes studied here nor on its surface/volume ratio.…”

supporting

confidence: 73%

Colloidal Synthesis and Optical Properties of Perovskite-Inspired Cesium Zirconium Halide Nanocrystals

Abfalterer

Shamsi

Kubicki

et al. 2020

ACS Materials Lett.

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Optoelectronic devices based on lead halide perovskites are processed in facile ways, yet are remarkably efficient. There are extensive research efforts investigating lead-free perovskite and perovskite-related compounds, yet there are challenges to synthesize these materials in forms that can be directly integrated into thin film devices rather than as bulk powders. Here, we report on the colloidal synthesis and characterization of lead-free, antifluorite Cs 2 ZrX 6 (X = Cl, Br) nanocrystals that are readily processed into thin films. We use transmission electron microscopy and powder X-ray diffraction measurements to determine their size and structural properties, and solid-state nuclear magnetic resonance measurements reveal the presence of oleate ligand, together with a disordered distribution of Cs surface sites. Density functional theory calculations reveal the band structure and fundamental band gaps of 5.06 and 3.91 eV for Cs 2 ZrCl 6 and Cs 2 ZrBr 6 , respectively, consistent with experimental values. Finally, we demonstrate that the Cs 2 ZrCl 6 and Cs 2 ZrBr 6 nanocrystal thin films exhibit tunable, broad white photoluminescence with quantum yields of 45% for the latter, with respective peaks in the blue and green spectral regions and mixed systems exhibiting properties between them. Our work represents a critical step toward the application of lead-free Cs 2 ZrX 6 nanocrystal thin films into next-generation light-emitting applications.

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supporting

confidence: 73%

Colloidal Synthesis and Optical Properties of Perovskite-Inspired Cesium Zirconium Halide Nanocrystals

Abfalterer

Shamsi

Kubicki

et al. 2020

ACS Materials Lett.

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“…2) demonstrates a little angular dependence in the (ac) plane. It was deduced to be produced by the ClF − molecular ion, very similar to the well-known Vk and H centers observed in halides [24][25][26][27], e.g., the 2 Cl − in Cs2HfCl6 reported recently [26,27]. In the present case, to prove the correct choice of the center's model, the experimental spectrum in Fig.…”

Section: X-ray Induced Centers In the Undoped Licaalf6supporting

confidence: 86%

“…Small temperature shift of the EPR decay curves with respect to the glow peaks is due to different setups used in EPR and TSL experiments and different ways of temperature measurement. The EPR decay curves were fitted with the recursive expression[27,29]:…”

mentioning

confidence: 99%

Undoped and Eu, Na co-doped LiCaAlF6 scintillation crystals: Paramagnetic centers, charge trapping and energy transfer properties

Buryi

Babin

Laguta

et al. 2021

Journal of Alloys and Compounds

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“…While nature of the V k (b) center is still to be clarified in further studies. Furthermore, based on results of RL, TSL and EPR combined measurements, authors from [39] came to the conclusion that better stoichiometry leads to simultaneous reduction of the number of both the emission centers (Hf-and Zr-based), as well as the trapping centers.…”

Section: Investigation Of the Defect Structurementioning

confidence: 99%

“…In order to study of the temperature dependence of the luminescence characteristics (before this publication only room-temperature studies on CHC were addressed) and to precisely determine of the emission and trapping centers, the same research group has applied the time-resolved luminescence spectroscopy and EPR techniques in a broad temperature range [39]. Authors synthesized a CHC compound following the procedure as described in [38], while the finally synthesized material was subsequently purified by a combination of gaseous halogenation agents introduced into its melt and zone-melting technique.…”

Section: Investigation Of the Defect Structurementioning

confidence: 99%

Novel Cs2HfCl6 Crystal Scintillator: Recent Progress and Perspectives

Nagorny

2021

Physics

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Recent progress in Cs2HfCl6 (CHC) crystal production achieved within the last five years is presented. Various aspects have been analyzed, including the chemical purity of raw materials, purification methods, optimization of the growth and thermal conditions, crystal characterization, defect structure, and internal radioactive background. Large volume, crack-free, and high quality CHC crystals with an ultimate scintillating performance were produced as a result of such extensive research and development (R & D) program. For example, the CHC crystal sample with dimensions ∅23 × 30 mm3 demonstrates energy resolution of 3.2% FWHM at 662 keV, the relative light output at the level of 30,000 ph/MeV and excellent linearity down to 20 keV. Additionally, this material exhibits excellent pulse shape discrimination ability and low internal background of less than 1 Bq/kg. Furthermore, attempts to produce a high quality CHC crystal resulted in research on this material optimization by constitution of either alkali ions (Cs to Tl), or main element (Hf to Zr), or halogen ions (Cl to Br, I, or their mixture in different ratio), as well as doping with various active ions (Te4+, Ce3+, Eu3+, etc.). This leads to a range of new established scintillating materials, such as Tl2HfCl6, Tl2ZrCl6, Cs2HfCl4Br2, Cs2HfCl3Br3, Cs2ZrCl6, and Cs2HfI6. To exploit the whole potential of these compounds, detailed studies of the material’s fundamental properties, and understanding of the variety of the luminescence mechanisms are required. This will help to understand the origin of the high light yield and possible paths to further extend it. Perspectives of CHC crystals and related materials as detectors for rare nuclear processes are also discussed.

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Trapping and Recombination Centers in Cesium Hafnium Chloride Single Crystals: EPR and TSL Study

Cited by 19 publications

References 40 publications

Colloidal Synthesis and Optical Properties of Perovskite-Inspired Cesium Zirconium Halide Nanocrystals

Colloidal Synthesis and Optical Properties of Perovskite-Inspired Cesium Zirconium Halide Nanocrystals

Undoped and Eu, Na co-doped LiCaAlF6 scintillation crystals: Paramagnetic centers, charge trapping and energy transfer properties

Novel Cs2HfCl6 Crystal Scintillator: Recent Progress and Perspectives

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